9- control of heart rate in mammals

Question 1

baroreceptors

Answer 1

• Found in the walls of the aorta, carotid arteries, and right atrium.
• Detects changes in blood pressure, and initiates impulses in response.

Question 2

chemoreceptors

Answer 2

• Found in the walls of the main arteries.
• Detects changes in blood chemistry (e.g. pH decrease due to CO2 and lactic acid).
• These receptors send impulses to the cardiac centre.

Question 3

cardiac centre

Answer 3

• The cardiovascular control centre is found in the medulla oblongata in the hindbrain.

Question 4

cardiac acceleratory region

Answer 4

Acts to increase the heart rate and force of contraction.

Question 5

cardiac inhibitory region

Answer 5

Acts to slow the heart rate and force of contraction.

Question 6

what do the regions in the cardiac centre do

Answer 6

The regions send impulses along the sympathetic or parasympathetic nerve.

Question 7

sympathetic (cardiac) nerve

Answer 7

Releases noradrenaline at the SAN to increase the heart rate.

Question 8

parasympathetic (vagus) nerve

Answer 8

Releases acetylcholine at the SAN to slow the heart rate.

Question 9

Sympathetic and parasympathetic nerves are

Answer 9

These nerves are antagonistic as they have opposite effects on heart rate.

Question 10

Understand the role of the autonomic nervous system in causing the release of adrenaline to increase heart rate.

Answer 10

• Sympathetic nerves stimulate the release of adrenaline and noradrenaline from the adrenal medulla.
• These are very similar in structure and have the same effect on heart rate and other bodily functions.